The invention relates to a water activatable layer on a substrate, to methods for producing a substrate containing a water activatable layer and to laminates made using a material containing a water activatable layer.
Relatively inexpensive novelty items containing hidden images are produced in large quantities and are used in a variety of applications including game pieces, food packaging prizes, educational children""s books and the like. Many of these items contain full color hidden images. The images may be developed or revealed by applying a developer or solvent to the hidden image area of the object. The disadvantage of many of these items is that the object can only be used once, and once the image is revealed, the object no longer has significant appeal. Another disadvantage of such objects is that the developer or solvent is often toxic or hazardous and thus could be dangerous when used by unsupervised children or infants.
In order to overcome the problems associated with the use of toxic developers or solvents, objects containing water activatable coatings were developed. When dry, the coatings are substantially opaque and thus effectively hide an underlying image from view. However, upon wetting the coating with water, the underlying image is revealed or is provided with full vibrant color. Once the object again dries, the coating becomes opaque and thus again hides the image from view. While such objects and image developers are less toxic than the solvents and developers used for other latent image objects, it is difficult to produce such objects in a cost effective manner in quantities which enable reasonable profits to the manufacturers and distributors thereof
Despite the advances in the art of printing hidden or latent images, there remains a need for a cost effect material and method for applying the material to a substance to produce vibrant full color images upon activation.
Considering the foregoing, the present invention provides a laminate which includes a substrate having a first surface containing an image thereon and a polymeric film laminated to the first substrate surface overlying the image. The film contains an exposed water activatable opaque layer having a thickness ranging from about 0.60 mil to about 2.0 mil wherein the opaque layer comprises aluminum silicate and a binder.
Another aspect of the invention provides a method for coating a polymeric film with a water activatable opaque layer. According to the method, a polymeric film having a first surface and a second surface is provided and an opaque water activatable material is applied to the first surface of the film using a Meyer rod coating technique. After applying the material to the film, the material is dried.
Still another aspect of the invention provides a method for making a novelty item containing a water revealable image which includes providing a porous web, printing an image on a surface of the web, applying an opaque water activatable coating to a first surface of a polymeric film by means of a Meyer rod coating technique, drying the coating to obtain an opaque layer on the film, and laminating the film to the porous web so that the image is between the porous web and a second surface of the film and the opaque layer is exposed.
An important advantage of the invention is that objects containing the opaque coating may be produced in high volume using the techniques described herein. Another advantage of the invention is that the opaque coated film may be applied to a variety of substrates containing images which may be black and white or full color images. Still another advantage of the invention is that the image containing substrate and film containing an opaque layer may be produced separately in the same or remote locations and combined later into a single composite material.